Vacuum extraction technology (VET) has recently become a highly popular process in chemical spill cleanups. VET involves the drilling of extraction and injection wells in the area of the plume as shown in U.S. Pat. Nos. 4,593,760, 4,660,639, 4,730,672, and 4,890,673. The wells formed in these processes generally include a conduit which is inserted into the borehole with permeable and impermeable fill material packed around the conduit. In U.S. Pat. Nos. 4,593,760 and 4,660,639, a perforated conduit is utilized in the extraction wells to attempt to draw contaminants along the entire lower length of the conduit. In my U.S. Pat. Nos. 4,730,672 and 4,890,678, a conduit having a single bottom opening is used.
The well construction shown in these patents are not totally efficient in removing volatile organic contaminants (VOC) from the earth strata. Such constructions do not achieve equal fluid movement throughout the length of the borehole which results in extra wells being drilled at different depths to ensure that all VOC's are recovered. Further, these constructions encourage mobilization of the fill material into the pipe which can significantly slow the VOC recovery process.